This invention relates to an improvement to the External Insulation And Finish System (EIFS), especially the non-combustible variation to the External Insulated And Finish System, which is mandated, when a non-combustible high impact resistant wall panel is required per municipal building code or architect preference, especially in hurricane or tornado areas of the United States.
EIFS, which is a type of cladding for exterior building walls, is defined per ASTM E631-91b as a “a non-loading outdoor wall finish system consisting of a thermal insulation board, an attachment system, a reinforced base coat, exterior joint sealant, and a compatible finish”.
The development of EIFS occurred after World War II and was introduced to North America in the late 1960s or early 1970s as an EIFS called Dryvit™. While there are slight differences in the EIFS between the European and North American methods for the “System”, there are mandatory components for the EIFS wall cladding in both cases.
As described in detail later herein, the mandatory components of a typical prior art EIFS (see FIG. 1), are: an interior finish 1; an interior wallboard 2; a stud 3 and sheathing substrate system 4, which the EIFS is attached, such as wood sheathing, mineral boards, an exterior grade or glass fiber-faced gypsum board, or cement board; insulation made of expandable polystyrene 6; attachment means for attaching the insulation to the substrate; a base coat adhesive 7 with reinforcing mesh 8 embedded in the adhesive located over the outside face of the EPS insulation board; and the finish 9, which is basically an esthetic part of the EIFS and is the visible portion of the wall system. This finish coat is typically made from an acrylic resin, which is either troweled or sprayed on, and a joint sealant system of which there are several types. Items 7, 8 and 9 are collectively referred to as the EIFS' “ lamina”.
The EIFS cladding is typically comprised of at least those components as described above. Each component has its own specification(s) with several manufacturers supplying any one component. A critical component of the system is the Expandable Polystyrene (EPS) insulation board. Expandable Polystyrene comes to the molding facility looking very much like a grain of sand, with a weight per cubic foot of about 64 pounds. The polystyrene beads included a thin outer layer of polystyrene and a hollow interior that includes a blowing agent, such as pentane. In pre-expanding, the beads are expanded by applying heat through hot air or steam, which causes the blowing agent to vaporize and expand the bead, to the desired density required for the second step, which is to mold the beads, through heat, steam, pressure and cooling, into the desired construct, for example; a panel, packaging material or helmet. Each construct has its own desired density requirements. In the EIFS industry the EPS beads are pre-expanded to its desired weight, which is from 0.9 to 1.1 pound(s) per cubic foot. This weight is about at the lowest limit EPS it can be pre-expanded to and molded.
In the EIFS industry this EPS board is required to have very specific characteristics, such as, it can be no less than ¾ of an inch thick, nor more than 4 inches thick, and needs to be pre-expanded to and molded at a density of one pound per cubic foot, plus or minus ten percent. EPS at one-pound density acts as a buffer or type of “shock” absorber, between the substrate and the “lamina”, which is the base coat, mesh and finish or esthetic coat, as described as items 7, 8, and 9 above. The ability of the EPS to flex as the substrate moves, or the lamina expand and contracts, allows the EPS to absorb the energy of a shearing movement and to minimize the energy or stop the shearing energy from passing through the EPS to the lamina, which could cause it to crack and/or deform. EPS at a density of more than 1 pound per cubic foot is stiffer and has been found to not give the EPS board the elasticity, which helps to prevent deforming or cracking in the lamina. Accordingly, with EPS board made at higher densities the greater the tendency to transfer any build up of forces from the substrate to the lamina, that might otherwise cause deforming or cracking. In fact, EIFS manufacturers will not warrant their systems if the EPS insulation board is of the wrong density. By not using EPS and by instead applying the lamina directly to a substrate, any build up of forces in the substrate may be passed directly through it and could cause cracking in the lamina. The above describes the components, which are the integral parts of the External Insulated and Finish System (EIFS), and outlines why the EPS panels have a requirement by the EIFS manufacturers that the EPS board by made at 0.9 to 1-density.
It is known in the art that the EIFS cladding, when used in hurricane or tornado parts of the United States, are modified to include at least two more layers of mesh, in order to withstand the high impact of a foreign object as might occur during a hurricane or tornado. As later described in detail, FIG. 2 depicts a prior art cladding construct modified to withstand heavy impacts. These extra layers of mesh are required because EPS at one-pound density while flexible, is very fragile and can be crushed or punctured rather easily, when it is made with the industry standard base coat, fiberglass mesh and finish material, as depicted in FIG. 1 and noted as numbers 7,8 and 9. Building codes, such as those in Miami-Dade County Fla., have adopted a Hurricane Protocol. A component of the testing protocol is PA 201, the “Large Missile Impact Test”, which is becoming the standard for building codes in hurricane and tornado regions of this country. There are several elements to the testing protocol, but of major concern in the EIFS industry is passing the large missile impact test. In this test, a 2×4 wood framing stud, about 9 feet long, is propelled from a “canon” at a speed of about 42 miles an hour at the surface of the object that is to be tested. The missile must not penetrate through the object tested to the inside of said object, or a test failure will occur. In the case of a wall panel, the missile must not crack or puncture the substrate so that light may be visible from the inside of the exterior wall cavity to an outside light source.
Improvements in the construction, with substantial cost savings of the above described External Insulated and Finish System, EIFS, are provided in accordance with this invention to achieve the same high impact non-combustible resistant panel system by providing a panel construct where the use of a high density expandable polystyrene panel, as is described in the teaching by Cutler in U.S. Pat. No. 5,718,968, is used in place of a layer of heavy weight fiberglass mesh. By using a high density EPS panel in place of a layer of fiberglass mesh, a savings in time and cost is achieved by doing away with the cost of the fiberglass mesh, the application of the adhesive, and the time and labor involved with embedding the fiberglass into the adhesive, with the attendant “down time” because of the need to allow the adhesive to dry and “set up”.
By simply attaching, through screwing, gluing or nailing, the high density panel to the stud or its backing, a rather inexpensive alternative to the prior art EIFS has been accomplished. This high density panel at about 2 foot by 4 foot in dimension can be attached simply and quickly, especially when working on scaffolding many floors off of the ground since it is reasonably light in weight yet offers the impact resistance that is currently required in the EIFS construct by building codes in certain hurricane and tornado areas of the country.
The present invention provides an exceptionally strong non-combustible Expandable Polystyrene And Fixed System construct at a substantial cost savings over typical EIFS prior art systems, as are outlined in FIGS. 1 and 2. Saving is achieved without sacrifice in impact resistance by employing a high density Expandable Polystyrene (EPS) panel/board in place of a layer of high impact reinforcing as shown in FIG. 3, a single layer of high impact reinforcing mesh is then attached to the high density board, and then a layer of conventional 1-pound EPS board with a light weight mesh embedded in an adhesive; a finish material, such as a stucco material or acrylic based finish coat, is then applied.
In accordance with the foregoing objective, a high impact resistant EIFS construct is achieved by using the high density EPS panel in lieu of a layer of fiberglass mesh, having the advantage of a time saving method with low cost, and ease of construction, over the standard EIFS claddings as are furnished by the various EIFS manufacturers.